Chassis, generic

C0633 Front Half Shaft Speed Sensor

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

On all-wheel-drive systems that can uncouple the front axle, a speed sensor on a front shaft tells the controller how fast the uncoupled part turns, so it can match speeds before re-engaging. A BorgWarner patent uses a Hall sensor on the shift sleeve to read both speed and position and engages once the gap to wheel speed is within about ±100–200 rpm; an American Axle patent uses a pinion speed sensor the same way before moving its shift collar. Ford documents C0633 in the AWD module of 2020 Explorer, Aviator and Police Interceptor Utility 4WD built up to 20 Mar 2020: warning messages with C0633, C00A6:07 or both came from an oil-soaked front halfshaft speed sensor; TSB 21-2270 replaces it (0.8 h).

Likely causes

Sensor contaminated with axle oil (Ford Explorer/Aviator 2020)
Failed sensor or damaged wiring and connector
Wrong air gap or damaged sensor target on the shaft

Symptoms

  • AWD or 4WD warning messages in the cluster
  • All-wheel drive limited or not engaging
  • Possible oil seepage near the sensor

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–350
Time0.5–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

front halfshaft speed sensorawd control module

Related codes

C0631C0632C00A6C05F3

References: static.nhtsa.gov, patents.google.com, patents.google.com.